[ntp:questions] avoiding large steps (on time island)

seanjlangford at gmail.com seanjlangford at gmail.com
Mon May 21 20:07:53 UTC 2007


On May 17, 11:55 am, "Richard B. Gilbert" <rgilber... at comcast.net>
wrote:
> seanjlangf... at gmail.com wrote:
> > I'm having some trouble with a 'time island' type configuration;  I
> > have a number of ntp clients connecting to one ntp server using its
> > local clock driver (127.127.1.0).  This network is isolated from the
> > rest of the world, and for this application, having universally
> > correct time is far less important than having 'node-relative'
> > accurate time.  I have a problem scenario where the client starts
> > *before* the server and misses the opportunity to do the one time sync
> > to the server (ntp -g).  Then sometime after the server boots, the
> > clients clocks make large steps to correct the difference (with a
> > 'time reset' ntp log message).   This is causing hangs in our client
> > application software as it uses software timers.  Is there a way to
> > limit the size of a step? or spread it out over time more slowly?  I
> > am aware of the -x flag, but would rather to continue to step, but in
> > smaller sizes.
>
> > Cheers
>
> > Sean
>
> > Client config:
>
> > tinker panic 0
> > logfile /var/log/ntpd.log
> > driftfile /var/lib/ntp/drift
> > server 192.168.2.163 prefer
> > fudge 192.168.2.163
>
> > Server config:
>
> > logfile /var/log/ntpd.log
> > driftfile /var/lib/ntp/drift
> > server  127.127.1.0 iburst minpoll 4
> > fudge 127.127.1.0 stratum 10 prefer
>
> The simplest thing to do would be to start the server before the client
> or just never shut the server down!

Richard,

Thanks for your suggestion.  Unfortunately these are not computers in
the traditional sense; they are a collection of portable devices which
are connecting/disconnecting from the network and powering up/down
arbitrarily.

Cheers

Sean




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